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Commit 7d1a9417 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86: Use generic idle loop 



Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: default avatarSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130321215235.486594473@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
parent aba92c9e

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -97,6 +97,7 @@ config X86 
	select GENERIC_IOMAP

	select DCACHE_WORD_ACCESS

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_IDLE_LOOP

	select ARCH_WANT_IPC_PARSE_VERSION if X86_32

	select HAVE_ARCH_SECCOMP_FILTER

	select BUILDTIME_EXTABLE_SORT

arch/x86/kernel/process.c

+27 −78
Original line number Diff line number Diff line
@@ -301,13 +301,7 @@ void exit_idle(void) 
}

#endif



/*

 * The idle thread. There's no useful work to be

 * done, so just try to conserve power and have a

 * low exit latency (ie sit in a loop waiting for

 * somebody to say that they'd like to reschedule)

 */

void cpu_idle(void)

void arch_cpu_idle_prepare(void)

{

	/*

	 * If we're the non-boot CPU, nothing set the stack canary up
@@ -317,71 +311,40 @@ void cpu_idle(void) 
	 * canaries already on the stack wont ever trigger).

	 */

	boot_init_stack_canary();

	current_thread_info()->status |= TS_POLLING;

}



	while (1) {

		tick_nohz_idle_enter();

void arch_cpu_idle_enter(void)

{

	local_touch_nmi();

	enter_idle();

}



		while (!need_resched()) {

			rmb();

void arch_cpu_idle_exit(void)

{

	__exit_idle();

}



			if (cpu_is_offline(smp_processor_id()))

void arch_cpu_idle_dead(void)

{

	play_dead();

}



/*

			 * Idle routines should keep interrupts disabled

			 * from here on, until they go to idle.

			 * Otherwise, idle callbacks can misfire.

 * Called from the generic idle code.

 */

			local_touch_nmi();

			local_irq_disable();



			enter_idle();



			/* Don't trace irqs off for idle */

			stop_critical_timings();



			/* enter_idle() needs rcu for notifiers */

			rcu_idle_enter();



void arch_cpu_idle(void)

{

	if (cpuidle_idle_call())

		x86_idle();



			rcu_idle_exit();

			start_critical_timings();



			/* In many cases the interrupt that ended idle

			   has already called exit_idle. But some idle

			   loops can be woken up without interrupt. */

			__exit_idle();

		}



		tick_nohz_idle_exit();

		preempt_enable_no_resched();

		schedule();

		preempt_disable();

	}

}



/*

 * We use this if we don't have any better

 * idle routine..

 * We use this if we don't have any better idle routine..

 */

void default_idle(void)

{

	trace_cpu_idle_rcuidle(1, smp_processor_id());

	current_thread_info()->status &= ~TS_POLLING;

	/*

	 * TS_POLLING-cleared state must be visible before we

	 * test NEED_RESCHED:

	 */

	smp_mb();



	if (!need_resched())

		safe_halt();	/* enables interrupts racelessly */

	else

		local_irq_enable();

	current_thread_info()->status |= TS_POLLING;

	safe_halt();

	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());

}

#ifdef CONFIG_APM_MODULE
@@ -411,20 +374,6 @@ void stop_this_cpu(void *dummy) 
		halt();

}



/*

 * On SMP it's slightly faster (but much more power-consuming!)

 * to poll the ->work.need_resched flag instead of waiting for the

 * cross-CPU IPI to arrive. Use this option with caution.

 */

static void poll_idle(void)

{

	trace_cpu_idle_rcuidle(0, smp_processor_id());

	local_irq_enable();

	while (!need_resched())

		cpu_relax();

	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());

}



bool amd_e400_c1e_detected;

EXPORT_SYMBOL(amd_e400_c1e_detected);
@@ -489,10 +438,10 @@ static void amd_e400_idle(void) 
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)

{

#ifdef CONFIG_SMP

	if (x86_idle == poll_idle && smp_num_siblings > 1)

	if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)

		pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");

#endif

	if (x86_idle)

	if (x86_idle || boot_option_idle_override == IDLE_POLL)

		return;



	if (cpu_has_amd_erratum(amd_erratum_400)) {
@@ -517,8 +466,8 @@ static int __init idle_setup(char *str) 


	if (!strcmp(str, "poll")) {

		pr_info("using polling idle threads\n");

		x86_idle = poll_idle;

		boot_option_idle_override = IDLE_POLL;

		cpu_idle_poll_ctrl(true);

	} else if (!strcmp(str, "halt")) {

		/*

		 * When the boot option of idle=halt is added, halt is

arch/x86/kernel/smpboot.c

+1 −1
Original line number Diff line number Diff line
@@ -284,7 +284,7 @@ notrace static void __cpuinit start_secondary(void *unused) 
	x86_cpuinit.setup_percpu_clockev();



	wmb();

	cpu_idle();

	cpu_startup_entry(CPUHP_ONLINE);

}



void __init smp_store_boot_cpu_info(void)

arch/x86/xen/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ static void __cpuinit cpu_bringup(void) 
static void __cpuinit cpu_bringup_and_idle(void)

{

	cpu_bringup();

	cpu_idle();

	cpu_startup_entry(CPUHP_ONLINE);

}



static int xen_smp_intr_init(unsigned int cpu)